Fix your aching back, rebuild your shrinking brain

Melissa Healy, Los Angeles Times/ For the Booster Shots Blog

Chronic pain can bring on depression, problems of memory and concentration, and general brain fog-- a fact well known to many of the 50 million American adults who live with pain that has settled in for a long stay. But a study published Wednesday finds that changes in the brain that come with chronic pain can be reversed when the hurt is treated effectively.

The study, published in the Journal of Neuroscience, looked at sufferers of chronic low-back pain--a substantial slice of those with daily pain -- and compared their brain responses to cognitive tests and their brains' structures before and after they got treatment. They also compared the brain structure and function of chronic pain sufferers against those of a control group without chronic pain.

Compared with their 16 pain-free peers, the 18 subjects suffering chronic low-back pain had brains that were thinner and less densely packed in six specific regions of the brain. Three of those regions reside in the frontal cortex, which plays many pivotal roles in attention, judgment and reasoning. But other regions affected by the thinning help process mood, pain signals and judgments about what those around us are thinking and doing.

Six months after getting spine surgery or receiving long-acting analgesic injections to the lower back, 14 of the original 18 subjects came back for more brain scans and cognitive tests. While several regions of the brain remained thinner compared with controls, one region of the brain--the dorsolateral prefrontal cortex--appeared to have regenerated itself in the treated subjects, and was no longer thinner than the same region in the brains of the control group. During a challenging cognitive test, the differences in brain activation that had separated the chronic pain sufferers from the healthy controls also disappeared.

Why might a robust dorsolateral prefrontal cortex be better than one hobbled by chronic pain? Because this area plays a key role in mood, social judgment, short-term memory and higher-order thinking, and any or all might suffer with the loss of cell density in the region.

And when researchers took into account whether the back treatment had worked, the brain comeback of patients freed of pain showed even greater strength. Three of the 14 treated patients reported worse back pain or disability six months later, and when researchers looked at their brain scans alone, it became clear their gray matter had not regenerated itself at all.